Air can be fractionalized by removing various components thereof through the affinity of these components with various molecular sieve materials. Apparatus for fractionalization can be found in U.S. Pat. Nos. 2,944,627, 3,280,536 and 3,142,547. In these cases, air under pressure is communicated to containers holding the molecular sieve material. It has been found that a molecular sieve material having an Angstrom pore size of 5 will continually produce an oxygen enriched effluent by the so-called pressure swing technique. In the above referred to patents, in achieving the proper flow of the air and oxygen enriched effluent for the pressure swing technique, a plurality of control valves are located in the supply conduit and the output conduit. The operation of the control valves are usually controlled by a timer to develop the maximum efficiency for the desired oxygen concentration in the enriched effluent. Because of the presence of inert gases in air the maximum concentration achievable will be 96%.